Skim coating old plaster ceiling


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Old 08-22-13, 07:06 PM
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Skim coating old plaster ceiling

The 16x12 plaster ceiling of my 80-year-old basement has some texture that I want to be rid of. I am not sure when the ceiling was last painted, of which type of paint was used (doesn't seem to be flat latex ceiling paint). There are some bubbles in the paint film, but this problem is limited to a couple of areas. There is a small crack in a corner (exposed lath), which will be repaired. I asked a general contractor (who is not a professional painter but who does painting as part of his business) who is doing a bunch of things to skim coat and paint the ceiling. To my surprise, he said he doesn't recommend skim coating. Instead he recommends putting drywall on top (bottom?) of the plaster to have a smooth base. He says that the skim coat will fall off.

This doesn't make sense to me. I thought scrapping the bubbles, spot priming (or perhaps complete priming) with zinsser 123, then skim coat with easy sand setting type lightweight join compound, then prime and paint would be fine. Is this a good strategy? Is there any reason why a ceiling like the one I described could not receive skim coating? Thanks
 
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Old 08-23-13, 03:42 AM
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Your contractor might figure it's easier to get a nice looking job by starting with fresh drywall.

Normally joint compound will adhere fine to clean latex paint. While it will also adhere to enamel it's best to scuff it up with sandpaper first. It would help to know if you have latex enamel or oil base on the ceiling - http://www.doityourself.com/forum/pa...latex-oil.html I would also be concerned as to why the existing paint has bubbled, is it related to the crack in the plaster?

What type of texture is currently on the ceiling? would it show up in a pic - http://www.doityourself.com/forum/el...-pictures.html
 
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Old 08-23-13, 05:09 AM
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Thanks for the reply. Pics attached.
 
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Old 08-23-13, 05:23 AM
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I'd check first to make sure it's latex enamel and not oil base. If it's latex, sand the ceiling with 60-80 grit and apply your j/c. If it's oil base, there is a chance it's lead based given the age of the house AND you don't want to sand lead based paint!! With lead based paint you have 2 choices; use a solvent based primer and then apply your j/c or cover it up as your contractor suggested.

The more I think about it, your contractor might be concerned about the possibility of lead base paint. The gov't came out with new regs concerning lead paint shortly after I retired. These regs limit what a contractor can do and can drastically increase the cost of dealing with lead based coatings. Homeowners have a little more leeway but I don't know how much Lead is mainly dangerous to children. The 2 biggest dangers are inhaling the dust [from sanding] and ingesting lead paint chips.
 
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Old 08-23-13, 05:45 AM
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A Textured Plaster Ceiling is the hardest to tape and repair cracks. Merely skim coating any ceiling cracks will not hold them shut and the cracks will re-appear shortly after you have finished the job. You will need to remove the thin veneer layer of plaster to expose the scratch coat on both sides of the crack, tape and cover with a setting type compound. You then may be able to skim the whole ceiling. I have on many occasions looked at this type of repair and determined that it is more cost effective and with better results to cover it with drywall. As the end result is a smooth surface, you do have the option of both choices. If the desire to repair only, it would be near impossible to match the random texture and not have it look like a patch.

Marksr - I don't think Lead Paint is a driver in this instance, the contractor would have had to have been upfront about that being an issue. He would have had to set up a containment zone, worn hazmat suit and respirator, Hepa-filtration system etc. This adds a tremendous cost to the price and the work zone would have been off limits during the process. And of course, he would have to be certified to perform the work or he would be breaking the law.
 
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Old 08-23-13, 05:46 AM
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Thanks. I don't think he's suggesting laminating for that reason -- a third suggestion was to demolish the ceiling and put new drywall! There are kids in the house so I said no to that idea.

My guess is that he is not the most experienced skim coater and he just find it easier to laminate. Would laminating take less time and less mess/dust than skim coating this ceiling? I know where the joist are (16 o/c). I was thinking of using 3/8 rock and perhaps some glue between rock and plaster to further minimize the risk of sagging.
 
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Old 08-23-13, 05:55 AM
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There is a little bit of 'art' to skim coating large areas and it would be easier for a novice to get a nice job with new drywall although IMO skim coating is less work. I'm not sure how well 3/8" drywall would work laminating it over a ceiling although adhesive between the joists would definitely help.
 
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Old 08-23-13, 06:08 AM
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I think it would be easier to skim coat a swirled ceiling as opposed the to knock down texture that you have. The skim coat smoothness would be dictated by the size of the largest bump in the texture. Looking at your picture, this may result in a very "bumpy" smooth texture. At the very best it will wave a little.

Would laminating take less time and less mess/dust than skim coating this ceiling?
No, it would be several (min.3) coats to the entire ceiling with and complete sanding as opposed to sanding the seams only. There will be dust either way though.
 
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Old 08-23-13, 06:14 PM
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Thanks. I think I'll go for the drywall . Will post a few questions in the walls and ceiling forum.
 
 

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